Remove usage of webrtc::ColorSpace::XXX:kInvalid

The kInvalid enum entries will be removed since they are not part of
the standard T-REC H.273. kUNSPECIFIED may be used instead.

Bug: webrtc:8651
Change-Id: I71ac3f5eebf73cb4188c5e15532b289a4be1bc50
Reviewed-on: https://chromium-review.googlesource.com/c/1343108
Reviewed-by: Emircan Uysaler <emircan@chromium.org>
Commit-Queue: Johannes Kron <kron@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609739}
1 file changed